Assessment of different ionic adjustment strategies in low-salinity water on the growth of Litopenaeus vannamei and microbial community stoichiometry in a synbiotic nursery system

The aim of this study was to evaluate different ionic adjustment strategies in oligohaline water on the growth of Litopenaeus vannamei and C:N:P stoichiometric ratios of the floc microbial community (MC) in synbiotic nursery system. A 35-day culture (2000 PL's/m³) was carried out in 60 L units in a completely randomized experimental design, with three treatments: T1—seawater diluted to a salinity of 2.5 g/L (control), T2—water with a salinity of 2.5 g/L with potassium (K?) adjusted and T3—water at a salinity of 2.5 g/L with its Ca:Mg:K ratio adjusted to 1:3:1, each treatment in triplicates. The MC of flocs and the dissolved fraction (DF) was separated by filtration, where MC >1.6 µm and DF <1.6 µm. The juveniles reached a final weight of 0.40 ± 0.09–0.49 ± 0.04 g, survival above 80% and an average yield of 0.69 ± 0.18–0.81 ± 0.02 kg/m³, without significant differences among the treatments. A stabilizing trend of C:P, C:N and N:P ratios of MC was observed considering the variations of C:N:P in the DF, indicating a homeostatic behaviour of the floc MC, as occurs in systems with high nutrient availability. Our results indicate that the major ions initial concentrations (Ca²⁺: 25.07 mg/L, Mg²⁺: 89.75 mg/L and K?: 25.00 mg/L), total alkalinity 100.00 mg/L and total hardness 433.30 mg/L provide conditions that do not limit shrimp growth in oligohaline water synbiotic nursery system.     

Inheritance of resistance to four cucurbit viruses in Cucurbita moschata

Cucurbita moschata cv. Nigerian Local has been used as a source of resistance to Zucchini yellow mosaic virus (ZYMV), Watermelon mosaic virus (WMV), Papaya ringspot virus W (PRSV-W) and Cucumber mosaic virus (CMV) in breeding both Cucurbita moschata and Cucurbita pepo. We used the F₁, F₂ and BC₁ generations derived from the cross C.-moschata cv. Waltham Butternut × Nigerian Local to study the inheritance of resistance to each of the viruses. We confirmed monogenic dominant resistance to ZYMV previously attributed to Zym, and we report monogenic dominant resistance to WMV and CMV which we propose to designate Wmv and Cmv, respectively. A single recessive gene, which we propose to designate prv, controls resistance to PRSV. DNA samples were extracted from a Waltham Butternut BC₁ F₁ population screened with ZYMV and analyzed using randomly amplified polymorphic DNA markers. No RAPD markers linked to ZYMV resistance were found. This revised version was published online in July 2006 with corrections to the Cover Date.     

Ultrahigh strength in nanocrystalline materials under shock loading

Molecular dynamics simulations of nanocrystalline copper under shock loading show an unexpected ultrahigh strength behind the shock front, with values up to twice those at low pressure. Partial and perfect dislocations, twinning, and debris from dislocation interactions are found behind the shock front. Results are interpreted in terms of the pressure dependence of both deformation mechanisms active at these grain sizes, namely dislocation-based plasticity and grain boundary sliding. These simulations, together with new shock experiments on nanocrystalline nickel, raise the possibility of achieving ultrahard materials during and after shock loading.     

The calicheamicin gene cluster and its iterative type I enediyne PKS

The enediynes exemplify nature's ingenuity. We have cloned and characterized the biosynthetic locus coding for perhaps the most notorious member of the nonchromoprotein enediyne family, calicheamicin. This gene cluster contains an unusual polyketide synthase (PKS) that is demonstrated to be essential for enediyne biosynthesis. Comparison of the calicheamicin locus with the locus encoding the chromoprotein enediyne C-1027 reveals that the enediyne PKS is highly conserved among these distinct enediyne families. Contrary to previous hypotheses, this suggests that the chromoprotein and nonchromoprotein enediynes are generated by similar biosynthetic pathways.     

Cloning of a Genomic DNA Encoding Caffeoyl-coenzyme A 3-<Emphasis Type="Italic">O</Emphasis>-methyltransferase of Citrus

In recent studies, we found that Apll (a PthA homologue) bound to three citrus proteins. Amino acid sequence analysis revealed that one of the target proteins was homologous to that of S-adenosyl-l-methionine : trans-caffeoyl-coenzyme A 3-O-methyltransferase (CCoAMT), an enzyme which is specific for the substrate trans-caffeoyl-CoA and catalyzes the synthesis of trans-feruloyl-CoA. From the consensus nucleotide sequences of CCoAMT genes, primers were chosen for PCR amplification of this gene from citrus total DNA. Two selected DNA fragments of 1.0 kb and 2.0 kb were obtained. These fragments were used as the probe to screen a citrus library. One clone, pCCl00, contained a 1.0-kb SalI fragment that hybridized to the probes. The nucleotide sequence of this fragment was determined in both directions. In this fragment, there was an open reading frame of 232 amino acids interrupted by an intron of 106 nt, and the deduced amino acid sequence had 95.9% homology to tobacco CCoAMT. Southern blot analysis of total citrus DNA showed that four EcoRI fragments hybridized to the probes, suggesting the presence of more than one copy of CCoAMT in the citrus DNA. Received 4 November 1999/ Accepted in revised form 26 November 1999     

Fertility in Holstein × Gyr cows in a subtropical environment after insemination with Gyr sex-sorted semen

Breeding records, including 649 inseminations during fall and winter at a dairy farm in a subtropical area of Western Mexico (24o N; 24°C, mean annual temperature 24°C) were analyzed to document effects of sex-sorted semen from commercial Gyr bullls, estrus synchronization protocol, inseminator, sire and environmental conditions on fertility of crossbred cows (Holstein × Gyr). Percentage of services resulting in pregnancies decreased sharply when sex-sorted semen was used (22.7 vs. 37.7%; P < 0.01). Although statistically not significant (P = 0.31), cows whose first insemination was in November experienced a numerically greater reduction (21 percentage points) in pregnancy rate compared to cows whose first insemination occurred in December. Substantial increases in services per pregnancy (4.71 ± 1.35 vs. 2.13–2.43; P < 0.01) were associated with the warmer month of the study period, November, compared to other winter months. Pregnancy rates of cows regardless of semen category (33%) were not affected by sire, temperature–humidity index and estrus synchronization protocol. Cows inseminated by one inseminator had higher pregnancy rates (P < 0.01) than cows inseminated by other two technicians. The sorted sperm produced 91% (142/156) female offspring. It was concluded that, under the field conditions of the present study, pregnancy rate with sexed semen was 15 percentage points lower than pregnancy rates using conventional semen, with 91% of female calves derived from sexed sperm.     

Exploratory analysis of differences in sperm morphology in Nelore and Gir (Bos indicus) bulls

The aim of this study was to evaluate the effects of breed and season on semen quality parameters of zebu bulls. Data (1,632 registers) of semen production from Gir (n?=?4) and Nelore (n?=?15) bulls were collected between October 2005 and November 2009. The ejaculates were collected twice a week during various seasons (summer, fall, winter, and spring) and evaluated for the following semen parameters: ejaculate volume, sperm concentration, sperm motility, forward progressive motility (FPM), and sperm morphology. Factor analysis was used to determine the relationship among variables. The effect of breed (Gir and Nelore) and season and their cross effect on each parameter and extracted factor were tested using ANOVA. A negative correlation (P?<?0.05) was observed between FPM and proximal droplet, as well as with abnormal loose head, abnormal small head, pouch formation, abnormal mid-peace, and strongly folded tail. Gir bull sperm showed more major defects, detached acrosome, and minor FPM (P?<?0.01), whereas Nelore bulls showed a higher number of sperm with normally loose head.